This invention relates generally to vertical turbine pumps and more particularly to multi-stage non-clog pumps for pumping fluids which may contain fibrous solids.
Vertical turbine pumps are commonly used for pumping sewage and other fluids which contain fibrous solids such as cloth, paper, and/or string. U.S. patent, for a FRONT REMOVABLE BEARING HOUSING FOR A VERTICAL TURBINE PUMP, U.S. Pat. No. 5,993,153, for an OPEN BOWL FOR A VERTICAL TURBINE PUMP describe such pumps and non-clog applications; and they are, in their entireties, incorporated herein by reference.
In some cases, the pressure head attainable with a single stage turbine pump is not sufficient to provide the lift required by the pumping task, and multiple stage pumps must be used as seen in FIG. 1 which illustrates a two-stage pump of the prior art. This may also be accomplished by making a "stack" of single stage pump bowls such as those described in the applications incorporated by reference. However, when such bowls are stacked, the impeller drive shaft is subject to entanglement by rags and other fibrous materials at the points where it passes from the impeller of an upper stage into the stationary pump bowl inner wall of each lower stage. This may result in blockage of flow, jamming the pump impeller, and even breakage of the impeller drive shaft. Clearance of such jamming and repair of such breakage may require complete disassembly of the pump and, thus, in deep pumping applications which require multi-stage pumps, may be very costly.
The foregoing illustrates limitations known to exist in present multiple stage turbine pumps for solids bearing fluids. It would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.